The invention relates to a speed control system for a work machine and more specifically to a speed control system for a compaction work machine that allows the operator to easily set a desired impact spacing
Large compacting work machines include rotatable drums with internal eccentric weights/vibratory mechanisms that are rotated to impose impact forces on a compactable surface being traversed, such as soil, roadway base aggregate, or asphalt paving material. The operator, to achieve maximum compactive effort and production efficiency for a given compacting operation, controls three functional settings of the compacting work machine. These settings are the frequency of the impact forces (# of impacts per unit of time e.g. vibrations per minute), propel speed of the compacting work machine (distance traveled per unit of time e.g. meters per minute), and impact spacing (# of impacts per distance traveled e.g. vibrations per meter).
Factors that influence the control of the three variables are experience of the operator and the simplicity or effectiveness of machine control systems. Different methods and machine control systems have been utilized to optimize the relationship of these three variables. One such system is disclosed in U.S. Pat. No. 5,719,338 issued Feb. 8, 1998 to Edward Magalski and assigned to Ingersoll-Rand Company. This system uses sensors to measure the rotational speed of the hydraulic motors used to propel the machine and to rotate the vibratory mechanisms. A signal is sent to a controller that compares the signal from the sensors and creates a signal indicative of the impact spacing. During a compacting operation the impact spacing signal is displayed on a gage. While effective this system makes the operator monitor the gage and control propel speed to ensure that the proper impact spacing is maintained all while steering the compacting work machine. Thus, causing the operator to monitor and control multiple functions of the compacting work machine simultaneously.
The present invention is directed to overcoming one or more of the problems as set forth above.
In one aspect of the present invention a speed control system for a work machine is provided. The speed control system includes a first input device that is adapted to produce a first signal indicative of a desired rotational speed of a fluid motor. A second input device is adapted to produce a second signal indicative of a desired propel speed. A third input device is adapted to produce a third signal indicative of a desired impact spacing. A controller receives the first signal, the second signal and the third signal, compares the first and second signals to the third signal and responsively produces an output signal.
In another aspect of the present invention a method for controlling the speed of a compaction work machine is provided. The method includes the steps of selecting a frequency setting from a first input device adapted to produce a first signal indicative of a desired rotational speed of a fluid motor. Then, selecting a propel speed from a second input device adapted to produce a second signal indicative of a desired propel speed. Next, selecting a desired impact spacing from a third input device adapted to produce a third signal indicative of a desired impact spacing. Then, comparing the frequency setting and the propel speed setting with the impact spacing setting. Lastly, responsively producing an output signal.